Theewnonic tube



Reissued July 28, 1936 UNITED STATES txaminer PATENT OFFICE THERMIONICTUBE Oran T. Mcllvaine, St. Charles, 11]., assignor to Mcllvaine PatentCorporation, St. Charles, 111., a corporation of Delaware Original No.1,853,914, dated April 12, 1932, Serial No. 28.401, May 6, 1925.Application for reissue September 14, 1934, Serial No. 743,990

9 Claims. (Cl. 250-275) This invention relates to thermionic tubes suchas are employed in the reception, detection "rand amplification Of IadlOmessages and 3150 in telephone repeating and amplification, and

If other instances or amplification and magnification of electricalimpulses.

The customary mode of generating negative electrons is to use a metallicfilament heated electrically, and it has always heretofore beennecessary to employ an absolutely steady direct current for this purposesince any variation in the current caused similar variations in thereception wires. Thus the employment of alternating current produced ahum which obliterated all signals, and the customary mode heretoforefollowed has been to energize the emitting filament by the use of aprimary or storage battery.

The object of the present invention is the provision of a tube of thischaracter which can be connected directly to an alternating currentsupply of the requisite voltage and which will exhibit the same mode ofoperation as with a direct current source, entirely without hummingsounds or other noises; the provision of a new arrangement of filamentswhereby variations in direction and potential oi. the current flow maybe neutralized; while other objects and advantages of the invention willbecome apparent as the description proceeds.

In the drawing accompanying and forming a part of this application Ihave shown specimen modes of applying my invention to a standard tube ofone of the most widely known makes although it will be understood that Ido not limit myself to kind, appearance, or type of tube and have chosenthis solely for purposes oi illustrating the essential idea of myinvention without restricting myself to the arrangement shown.

Referring now to the drawing, Fig. 1 is a perspective View of a tube ofthe type described, portions of the elements being broken away in orderto show the internal construction; Fig. 2 is an enlarged view of thefilament and support, the plate and grid being entirely omitted; Figs.3, 4, and 5 are detail views showing other arrangements oi filaments;and Figs. 6 and 7 are detail views showing concentrated forms offilaments as desired for certain other types of tubes.

Practically all tubes comprise an evacuated glass globe I, a supportingbase 2, and certain metallic elements enclosed within the tube andcomprising in one guise or another, a plate 3, grid 4 and filaments 5and 6. Ordinarily the filaments consist of a single circuit butaccording to my invention I make said filaments of even numbers ofplural strands located closely together and connected between theterminals or the alternating current in reversed positions, thefilaments being so arranged as regards other elements that theelectrostatic condition created by one filament shall be neutralized bythe other filament, with the result of producing a steady source ofnegative electrons.

Thus, in the form shown in Figs. 1 and 2 the various wires are broughtinto the tube through a press I in which numerous wires are sealed suchas the wires 8, which carry the plate, the wires 9, which carry the gridand the connections I0, II, which carry the filaments. The connectionII), in addition to receiving the lower end of the filament 5 alsocarries a bracket I2 terminating at its upper end in a hook I3 whichsupports the upper end of the companion filament 5. Likewise theconnection II carries a bracket I4 which terminates at its upper end ina hook I5 to which is secured the upper end of the filament 5.Preferably in practice these brackets I2 and I4 are located outside ofthe tube elements as shown in Fig. l and the reversal oi the connectionsof the corresponding ends or the adjacent filaments provides anon-inductive circuit through such filaments.

The filament and elements are connected to base contacts in the usualmanner and in use the wires in, II are connected to opposite ends of thesecondary winding it of a transformer IT whose primary winding I8 isconnected to any suitable supply of alternating current such as theordinary lighting circuit. Any suitable or desired voltage may beemployed although I have been particularly successful with the use of arather large current and small voltage, the latter about to 1 volt. Thishas the further advantage of enabling the use of heavier and strongerfilament wires than can be used in higher voltages.

If we assume at any given instant that the wire II! is positive and thewire II negative, due to the fluctuations in the circuit, then the lowerend of the filament 5 will be positive and the lower end of the filament6 negative and at the same time, owing to the fact that the brackets I2and II have substantially a zero resistance the upper end of thefilament 6 is positive.

In other words the A. 0. wave starts simultaneously at opposite ends ofthe two filaments, and as the wave progresses, it progresses exactly thesame in both filaments, that point which was before highly positivegradually decreasing and that point which before was highly negativegradually approaching positive until the two reach the same condition,which occurs midway of the wave, after which the lower end of thefilament 5 becomes increasingly negative and the lower end of thefilament 6 increasingly positive. Considered in another aspect it can bepictured that alternating waves are constantly chasing each other up anddown the respective filaments but are so related, one to the other, thatthe algebraic sum of such waves at equal horizontal levels in therespective filaments is always zero.

This is readily seen at the instant of highest potential in one of thefilaments, at which time the corresponding point in the other filamentexhibits its correspondingly low potential, and if these filaments aresufiiciently close together the electrostatic charge on the one exactlyequals that on the other; and is likewise true when as a result of theadvance of a wave a given point of one filament becomes zero relative tooutside standards at which instant the corresponding point of the otherfilament should always exhibit zero potential. As a result both wiresare always maintained under suflicient temperature to produce anadequate supply of electrons, without at the same time causing thealternating current oi. the lighting systems to influence the receptionsince a positive condition at each point of each filament is exactlycounterbalanced by an equivalent negative on the nearest segment of thecompanion filament.

These filaments may be supported and looped in a great many modeswithout departure from the scope of my invention or avoiding this modeof operation. The arrangement illustrated in Figs 1 and 2 is in manyways the simplest and most practical. However, it is equally possiblewhenever desired to increase the number of filaments as for example bymaking them in small segments as shown in Fig. 3 in which case the wiresl0 and H are provided with brackets I3, I3 15, l5 respectively adaptedto support the segments 5, and G the lower ends or the segments beingsuitably connected to the other wires to which their respective upperends were attached.

Another mode of arrangement is shown in Fig. 4 wherein the filaments 5and i are connected at their upper and bottom ends to the wires Ill andIl these filaments being made of any suitable material. In the form ofthe invention shown in Figs. 1 and 2 I have shown tungsten wires. Thesemay, if desired, have their emissivity increased by a coating ofrefractory earths such as thoria, and the greater thickness of thefilaments as in Fig. 3 is intended to indicate this. In Fig. 4 I haveshown these filaments as consisting of thin strips or ribbons of nickel,which also may, if desired, be treated superficially to increase theemissivity. In this case it is not necessary to keep the filaments apartat the center since this point always exhibits equal potential on thetwo filaments.

In the form shown in Fig. 5 the filaments instead of making only oneconnection between the wires Ill and are looped back and forthrepeatedly. The forms shown in Figs. 6 and 7 are devised for a moreconcentrated arrangement. In Fig. 6 the supporting wires In and I2 arecrossed but insulated from each other at the center, their extremitiesbeing surrounded by tile.- ments 5 6 here making a completeparallelogram; and in Fig. 'l the filaments 5 6 are shown as woundtogether into a double spiralythe ends being connected to the terminalsI0 I I It is not important whether the filaments 5 and 6 be parallel toeach other as they appear to be in Fig. 2 or somewhat inclined as inFigs. 1, 4. and 5, provided only that they be substantially parallel tothe face of the anode and that they be symmetrical with respect to astraight line which is parallel to the face of said anode. This axis ofsymmetry may either be vertical as in the form of Fig. 1 or transverseas in Fig. 5. Indeed in Figs. 4, 5, and 6 there are two rectangular axesof symmetry.

I have described the condition I have sought and here obtained by theexpression that the electrostatic eiTect produced by one filament isneutralized by another filament, or that the combined, external,electrostatic effect of those filaments is zero. This concept possiblyrequires additional elucidation. It is the purpose of my invention toobtain thermal emission of negative electrons by the use of analternating current. It has been known for many years that electrons aredriven off a metallic body by heating it. If the body be insulated fromother bodies the number of electrons that can be removed iscomparatively small since the abstraction of each negative charge leavesa corresponding positive charge on the body which tends to pull thecharges back.

In case the accumulated positive charge thus developed on the heatedbody be neutralized or discharged in any way more electrons are freed.This can be done by attaching the body to the negative pole of a highpotential battery such as 3 the B battery used in radio work, especially1': the other pole of the same battery be brought sufllciently near toreceive the negative electrons so emitted.

When an electric current is used to heat the body a second set ofelectrons is employed at the same time, the hypothesis being that thiscurrent is merely the passage of a different set of electrons throughthe body, and the heating effect a. symptom of resistance to the passageof those electrons. Although the two currents traverse the same body,namely the current which causes the heat and the current which causesthe electronic emission, they are entirely separate and distinct andindependent.-

It is hardly believed that the individual electrons which enter with theheating current always escape with that current and vice versa any morethan the individual drops of water that enter a reservoir through twopipes leave that reservoir through any given pipes. Presumably theelectrons are devoid of individuality so that it is merely requisitethat the same number per second leave the body over the respectivecircuits as entered it by those circuits, but as long as the heatingcircuit is uniform in potential its electrostatic effect can be ignored.

Now if the potential of either circuit be varied,

the rate of electronic emission must likewise vary.

It the B battery be removed or made more feeble the number of electronswhich can be released is likewise reduced; and if the body be heated byan alternating current its potential constantly in accordance with thephase of the E. M. F. will vary and ordinarily tends to influence theelectron emission in like proportion. It is for the purpose ofneutralizing this eflect that I employ plural bodies (in this case thefilaments 5, li.) so arranged that when a given point of one shall bepositive the corresponding point of the other shall be negative. This isexpressed briefiy by the statement that the combined electrostaticeffect of the two bodies (filaments) is zero.

It appears not to be necessary that the two bodies be so close togetherat every point as to efifect such neutralization at every point; indeedit is arguable that this condition might cause the one which chancedmomentarily to be positive to absorb all the electrons emitted at thatinstant by the other body. It'is only necessary that their combinedelectrostatic effect upon adjacent bodies or elements as a whole shouldbe neutralized, leaving the heating effect tree to release the electronsin the same manner as in the case of any other mode or heating.

The fact that the result in view can be obtained by any one of thevarious arrangements of filaments shown herein indicates that it is thetotal summation eflect which is important and not the detailed efiect atgiven points. This fact further indicates that numerous other detailedarrangements or filaments and elements can be employed with successfulresults, wherefore I do not restrict myself to the arrangements, ordesigns, or connections herein shown, nor in any other manner except asrecited in my several claims.

Having thus described my invention what I claim is:

1. A cathode struc ure comprising, a plurality of allel non-contiguousfilaments, and a pair of curreht supplying supporting members connectedto the opposite terminals of said filaments adapted to conductelectrical energy from an outside source to the said filaments, theadjacent terminals of the said filaments being reversely connected tosaid current supplying supporting mem bers.

2. A thermionic tube comprising, a hollow envelope, plate and gridelements and an even number of incandescible filaments therein, each 0!said filaments having a part lying substantially alongside or aneighboring filament, a pair of terminal members sealed in said envelopeadapted for connection to a source of alternating current, andconductors reversely connecting the corresponding ends of said filamentsto said terminal members whereby the instantaneous direction of currentfiow in the neighboring parts of the filaments is substantiallyopposite.

3. A thermionic tube comprising, a hollow envelope, an anode and acathode structure therein, said cathode structure including a pluralityoi resistance wires with a portion of each of such resistance wiresadjacent to but out of contact with a corresponding portion 01' anotherof such resistance wires, and a pair or terminal members sealed in saidenvelope and reversely connected to adjacent ends of the resistancewires of said cathode structure whereby the potential difference of suchends is substantially equal to the potential difference of the oppositeends of the same wires at any instant when the wires are connected incircuit with an ordinary alternating current supply system.

4. A thermionic tube having therein a plate, a grid, and a cathodecomprising a pair of parallel arranged filaments defining a filamentarystructure with adjacent non-contiguous portions, and a pair of terminalsreversely connected to each Examiner of the two corresponding ends ofthe filaments or said filamentary structure whereby such ends aremaintained at corresponding difierences of potential when said terminalsare connected in circuit with the ordinary alternating current lightingsystem.

5. A thermionic tube comprising, a plurality of incandescible filamentsmounted one alongside the other in closely spaced relation, a gridelement extending about said filaments, a plate element extending aboutsaid grid element, and terminal members alongside said plate element atthe side remote from said grid element and reversely connected to theopposite ends of said filaments whereby the adjacent ends of suchfilaments exhibit similar differences of potential when said terminalmembers are connected to an external source of alternating currentsupply.

6. A thermionic tube comprising, a pair or incandescible filamentsmounted one alongside the other in closely spaced relation, a gridelement surrounding said filaments, a plate element surrounding saidgrid element, and a pair of terminal members, one having a partconnected to an end of one of said filaments and another part connectedto the opposite end of the other of said filaments, the other of saidterminal members having corresponding parts connected in like manner tothe other ends of said filaments.

7. A thermionic tube comprising, a pair of closely adjacent parallelfilaments, each portion of one of said filaments being adjacent to butout oi contact with a corresponding portion of the other oi. saidfilaments, a grid element surrounding said filaments, a plate elementsurrounding said grid element, and a pair of terminal members, onehaving a part connected to an end of one of said filaments and anotherpart connected to the opposite end of the other of said filaments, theother of said terminal members having corresponding parts connected inlike manner to the other ends of said filaments.

8. An alternating current operated thermionic tube including a cathodecomprising a heater having a pair of adjacent filaments and a pair ofterminal members therefor adapted for connec-- tion to a source ofalternating current, the filaments each having a part lyingsubstantially alongside a neighboring filament, the adjacent ends ofsaid filaments being connected to opposite terminal members whereby thedirection of current fiow in said filaments is opposite and theinductive efi'ect oi the current flowing in one filament issubstantially neutralized by the inductive effect or the oppositelyflowing current in the other filament.

9. An alternating current operated thermionic tube having therein aplate, a grid and a cathode; said cathode comprising a filamentarystructure having a plurality of resistance wires, each wire having apart lying alongside a neighboring wire, and a pair or terminal membersseparately connected to the two pairs of adjacent ends of said wireswhereby the instantaneous direction of flow in the neighboring parts oithe wires is substantially opposite when the terminal connections areconnected to a source or alternating current sup- P y- ORAN 'I.McILVAINE.

